More tips which you may find useful:

Think about the metaphor, the meaning and the art of transformation.

As you develop your world view you need to think how your audience will be involved: What will make them buy into the world? What can they do? Does the world react to their actions? Do they have constructive activities?
Are they travellers? If so, do they carry anything with them -- maps,journals, a camera, a picnic basket? What can you expect them to know? from where?
Are they information seekers? What do they have access to? Can their access or use of information to information taint or otherwise change the world? How will participants spread the word? Will they appropriate a style of being? Will they gossip?

Is their influence on the story world determined or emergent?

When you think about the audience, bear in mind that they might have multiple, discrete interactions with the story. Certain members of the audience will have pagers. The pager network might be able to know something about what messages these people have received.

When you converge on themes for the world, and move on to the physical manifestation of the world and the behavioral nature of life in the world, you might want to develop two or more views of the world? A scary fire and brimstone view might be countered by a comic view of a little mechanical planetary sculpture which sits on a table and is observed by a cat. Extreme juxtapositions will allow transformations based on user activities. In addition, a member of the audience or a character might become bewitched and unable to distinguish whether their experience is real or imagined.

Now you can begin to play with the world, populating it with simple creatures. A person passes a display of a cat staring at the planetary system; they go on their way. More people pass by and suddenly the sculpture begins to burn.... Meanwhile another segment of the audience are on their way to a chat field to have a picnic; their mission, should they choose to accept it, might be to reset the master clock.....

Remember that we can layer and collage images in Isis. The world displayed in that technology can contain dynamic morphs.